Ultrathin Mesoporous Ionic Brushes Separator Enables Fast and Durable Zinc-Metal Aqueous Batteries.

Zinc metal aqueous batteries (ZnABs) emerge as promising candidates for grid-scale energy storage, yet severe Zn dendrite formation and anode side reactions degrade cycle life and hinder practical application. Herein, we report an ultrathin (27 µm) mesoporous ionic brushes (MiB) separator based on sulfonic grafted ordered mesoporous silica nanosheets for stable ZnABs. The well-ordered perforative mesopores architecture functions as an ion rectifier that achieves enhanced transfer kinetics and a homogeneous concentration field, thereby promoting dendrite-free deposition, as verified by in situ digital holography and kinetic analyses. Moreover, ionic brushes confined within nanochannels selectively capture water molecules from the primary solvation shell of Zn2+, facilitating desolvation and constructing a localized water-lean interfacial environment, which effectively suppresses water-related side reactions, as evidenced by various in situ spectroscopy, electrochemical analyses, and theoretical calculations. Consequently, the MiB separator enables the Zn anode to achieve a high Coulombic efficiency of 99.7%, ultralong lifespan over 4300 h, fast plating kinetics of 20 mA cm-2, and high Zn utilization rate of 51.6%. Furthermore, Zn-V2O5 cells achieve perdurable capacity retention of 91.5% after 3500 cycles. This work presents a rational mesoporous separator design that synchronously regulates ion transport and interfacial solvation chemistry for highly reversible ZnABs.